1. Field of the Invention
The present invention relates generally to the operation of hybrid vehicles, and more particularly to the operation of an engine of a hybrid electric vehicle.
2. Background Art
Methods for controlling the operation of an internal combustion engine in a hybrid vehicle are known in the hybrid vehicle engine control art, such as that described in U.S. Pat. No. 5,818,116. This patent focus on driving an internal combustion engine at a predetermined revolving speed to prevent variation in torque output at the time the internal combustion engine is started. However, it does not detail the specific steps for implementing fuel injection control and ignition timing control of the engine, nor does it address the vehicle emissions concerns associated with “overfueling” during engine startups.
Before applicants invention, there was a need for a method for controlling fuel injection during engine startups that more rapidly determines and provides a precise amount of fuel to provide to a particular engine cylinder to lower vehicle emissions. Moreover, there was a desire to inhibit “overfueling” conditions yet provide sufficient fuel to facilitate robust engine starts. Problems associated with the prior art as noted above and other problems are addressed by Applicants' invention as summarized below.